Authorities in Plaquemines Parish, where storm surge from Hurricane Isaac caused extensive flooding overnight, have ordered a mandatory evacuation for a portion of the west bank of the Mississippi River.
A shelter was to open at noon in Belle Chasse. Officials said the evacuation was ordered out of concern that more storm surge from Isaac would be pushed into the area and levees might be overtopped.
A mandatory evacuation earlier had been ordered for the parish's east bank, where a low levee was topped Wednesday morning, as well as for portions of the west bank.
Parish spokeswoman Caitlin Campbell said an 18-mile stretch from the St. Bernard Parish line at Braithwaite south to White Ditch was taking water and homes were flooding as storm surge piled up against levees between the Gulf of Mexico and the Mississippi River. Although an evacuation order had been issued as Isaac approached, sheriff's deputies from St. Bernard and Plaquemines parishes were going house-to-house getting residents who'd remained in the area to move to higher ground.
The Louisiana National Guard has moved 14 high-water vehicles and 10 boats into Braithwaite to help with evacuations.
"This is a local levee. They knew it's prone to flooding. That's why it was under a mandatory evacuation order. About 20 people or so didn't leave," said Col. Mike Edmonson, superintendent of Louisiana State Police.
"We're going to get out there to them. We're going to do everything we can to get them out of there. But we're not going to put further people in harm's way," Edmonson said.
With the storm expected to be moving across the state for hours, if not days, he said, "This is something we're going to be in for the long haul. This is not anywhere anytime soon."
Isaac bounced off the mouth of the Mississippi River Tuesday night, making its first landfall. It then moved onto Grand Isle, a barrier island in Jefferson Parish, where it stalled for several hours.
Jesse Delcambre, who stayed in the town hall because her fiance is a town employee, said the island was still covered by about 2 feet of water on Wednesday morning.
"The houses over here are all 12, 14 feet above ground on pilings," she said. The few on slabs are flooded, she added.
Jefferson Parish President John Young said the island may have been covered by up to 5 feet of water during the storm.
"I've been out and about since 3 o'clock this morning. The pump operators are keeping up, the pump stations are keeping up and working properly, so there's not a lot of street flooding," he said.
Any flooding reported was all in low-lying areas prone to flooding, he said.
"The 30 to 40 people who stayed there are accounted for and safe," he said.
Grand Isle, a resort prized for its sandy beaches — a rarity in marshy coastal Louisiana — is still recovering from the impact of the 2010 BP oil spill. There were no reports of remnant oil washing ashore.
Still Young said he was worried about his communities of Lafitte, Crown Point and Barataria. "We're waiting to see what happens with the Intercoastal Waterway. If it rises 5 to 6 feet we may have challenges there with coastal flooding and tidal flooding."
He wasn't aware of any floods there. "If the wind shifts to the south as expected, we're going to have some challenges."
Despite the overtopping of the levee, which stands 8 ½ feet, Campbell said streets in the area were still passable.
Parish President Billy Nungesser said a portion of the roof of his home on the parish's west bank had blown off. He described wind-driven rain coming into his home as "like standing in a light socket with a fire hose turned on."
Elsewhere, the storm drove sheets of rain through the nearly deserted streets of New Orleans as a population mindful of the powerful punch dealt by Hurricane Katrina seven years ago waited for the storm to get out of their lives. Isaac had stalled along the coast early Wednesday before resuming a move to the northwest several hours later.
Forecasters said the storm could drop up to 20 inches of rain, though city of New Orleans spokesman Ryan Berni said only minor street flooding and fallen trees were reported overnight.
He had no immediate reports of injuries or looting though he said one unoccupied structure had collapsed and there was a fire in a home caused by a candle. "Someone was reading by candlelight and the curtains caught fire," he added.
Thousands of law enforcement officers and Louisiana National Guard troops were poised for possible rescue efforts. Roadways in the city's eastern sector were reported flooded and trees were down.
Across Lake Pontchartrain in Slidell, Public Operations Director Mike Noto is asking city residents to flush toilets as little as possible. He says sewage tanks are about halfway full without anywhere to pump them, and the system is working at full capacity.
"This will not affect our drinking water, which we anticipate will remain available throughout the storm," said Noto.
Mayor Freddy Drennan said he drove through Slidell to check damage Wednesday morning, and saw only downed trees and power lines. "The city has not yet received any reports of water in homes," a news release said.
He said the westward movement would help the city, but the National Weather Service also had bad news: the storm had slowed down, extending the hours of maximum impact. An 8-foot storm surge was expected between noon and 2 p.m. Wednesday.
HESCO bags connected the levee system across Highway 11, but there was a chance that floodwaters could come over at the railroad tracks on the south side of town.
"While we've taken every measure possible to prevent this, unfortunately it remains a possibility," Drennan said. "It's unprecedented for a hurricane to bring tropical force winds for a 24- to 36- hour duration, and with that we will likely experience some atypical flooding. In addition to those areas which tend to flood during extensive rainfall, we may have some accumulation in areas which are normally dry. We don't anticipate the waters reaching anywhere near those of Hurricane Katrina, but want citizens to be prepared for some possible flooding. We also want to state emphatically that citizens should stay off the roads during this time."
Drennan said most of the city was without power, and conditions were still too dangerous for standby Cleco crews to attempt to restore power.
Floodgates were closed on area waterways to block Isaac's storm surge, part of the flood protection system rebuilt with billions of dollars of federal aid after Hurricane Katrina struck seven years ago. Large pumps designed to remove any floodwater from the low-lying level city on the Mississippi River were functioning as planned, Berni said. But he urged residents to remain vigilant and sheltered as long as the winds and rain bands were lashing New Orleans.
"We fully expect people to stay inside and not impede any efforts by our first responders," Berni said.
Early Wednesday, police officers were patrolling and TV news trucks moved about the streets of New Orleans where water ponded along the sides. The still-passable streets downtown didn't appear to be seriously flooded though some wind-blown tree branches and signs littered the ground.
Buildings in the downtown also didn't appear to have any significant damage.
At the International House Hotel, just outside the French Quarter, an early morning false alarm roused guests after windblown debris apparently shattered a window.
They were supposed to fly out of New Orleans on Wednesday after a vacation but the flight was canceled. It was deja-vu for the couple as they were trapped for two days in New York City last year when Irene, another hurricane, rolled up the Eastern Seaboard.
About 3 a.m. Wednesday, they were awakened by the sound of their hotel window shattering — possibly by flying debris.
It was a nerve-racking experience.
"I just don't know what to expect," Dewis said. "Hurricanes are so foreign to us."
She and her boyfriend joked that their next vacation probably won't be anywhere near a coastline.
"Definitely inland," she said. "Saskatchewan or something."
Meanwhile, more than half a million people were without power across the state's southern parishes, including more than 300,000 in New Orleans and its suburbs, power provider Entergy reported.
Though Isaac wasn't packing Katrina's punch, evacuations were mandatory in about a half-dozen parishes.
Coastal communities were largely abandoned after evacuation orders.
Houma, an oil patch community about 30 miles inland, was in darkness after power failed. The center of Isaac was expected to pass over the city as the storm slowly moved inland. Traffic signals swayed amid sheets of wind-driven rain as Isaac lurked nearby. Debris littered roadways.
Associated Press writer Michael Kunzelman contributed to this report.
Copyright 2012 The Associated Press.